Apparatus for sorting articles



Feb 1965 P. H. E. CLAESSON R 25,731

coumccr nsvxcs Criginal Filed March 8, 1956 i 1 5 INVENTOR PER HARRYLIA$ CLAESSON BY MM, Me u ATTORNEYS Reissued Feb. 16, 1965 25,731CONTACT DEVICE Per Harry Elias Claesson, Sportstugevagan 4, Danderyd,Sweden Original No. 2,924,684, dated Feb. 9, 1960, Ser. No.

570,331, Mar. 8, 1956. Application for reissue Dec. 23,

1963, Ser. No. 342,585

Claims priority, application Sweden, Mar. 11, 1955,

2,335/55 14 Claims. (Cl. 200-104) Matter enclosed in heavy bracketsappears in the original patent but forms no part of this reissuespecification; matter printed in italics indicates the additions made byreissue.

The present invention relates to contact devices of the kind comprisingcontact springs and being adapted for so called indirect operation.Contact devices of this kind have found wide use in electromagneticrelays, even in relays of the polarized type, and a relay may comprise aplurality of such contact devices, the contact springs being arranged inone or more groups.

- By indirect operation I mean a mode of operation according to which .acontact closure is effected by two contacts being moved into engagementdue to the action of the spring tension in at least one of the contactsprings which is released e.g. by the energization or release of arelay. Thus no external forces are acting upon the contact springsduring the closing process, whereas external means are used to keep thesprings out of engage- Inent when in non-operated position. In practiceone (called the movable spring) of the springs of a contact device forindirect operation is pre-tensioned or biased so, that it strives tomove its contact end towards the contact end of theother spring (calledthe fixed spring), and in non-operated condition the movable contactspring is kept separated from the fixed contact spring by means of alifting stud which may be operated e.g. by the armature of a relay.

Hitherto contacts with indirect operation have been used for the purposeof suppressing contact vibrations when two contacts strike against eachother (are closed). The springs to which the contacts are attached, havebeen made relatively long with a low natural frequency of vibrationwhereby the contacts have approached each other relatively slowly sothat the contact vibration at the first moment has been suppressed.Furthermore, the energy from detrimental vibrations of the movablecontact springs has been dissipated due to friction between the contactsand/or between the contact springs of a spring set so that it has beenpossible to eliminate even slow contact vibrations due to the lownatural frequency of vibration of the Contact springs.

However, the abovementioned design of the contacts also involves certaindrawbacks. Thus the contact devices become very susceptible toaccelerations and retardations and to shakings within the resonantfrequency range of the device, and consume large space and material andrequire considerable forces in order to yield rapid make and breakfunctions when the contacts are removed from each other.

It is an object of the present invention to provide a contact device ofthe kind defined aboveiwhich has no or little susceptibility toaccelerations and retardations and in which contact vibrations andbouncing are effectively suppressed.

The contact device according to the invention is foremost characterizedby the contact springs being pre-tensioned to such extent that theyyield a force at the contact points amounting to at least 30 times, forexample 50 times, the weight of the free endof the spring inclusive thecontacts.

It will be easily understood that a contact device having thischaracteristic will have little susceptibility to accelerations andretardations, but it is by no means obvious that it will also be freefrom contact vibrations and bouncing on closure, for there is no simplerelation between liability to contact vibrations and the ratio of thecontact pressure to the weight of the free ends of the contact springs.However, I have found that a contact device having the abovementionedcharacteristic shows a surprisingly high freedom from contactvibrations. The movements performed by the contacts during a closingoperation from the moment the contacts first touch each other till theyhave come to a state of rest or equilibrium, depend on a large number offactors, and therefore it has notbeen possible to explain theoreticallythe freedom from contact vibrations which is characteristic of thecontact device according to the invention.

When the contact on the movable contact spring strikes the contact onthe fixed contact spring, an elastic deformation of the contacts occurs,and thereby forces arise which strive to separate the contacts again.The movements of the contacts after the impact will not however bedetermined solely by the elasticity of the contacts but also to a highdegree by the properties of the springs .to which they are attached Onthe contact closure the fixed contact springwill be deflected from itsnormal position and thereby exert a force on the contact on the movablespring which force has a direction opposite to the initial direction ofmovement of said contact. Furthermore, that part of the movable contactspring which is situated between the fixed end of the spring and thecontact, will continue its movement after the contacts have first comeinto engagement, so that the movable spring will have a deflectionbetween the fixed end and the'contact. This deflection produces a forcewhich also acts upon the contacts and may be considered as an additionto the contact pressure which exists between the contacts when they havereached the state of rest. The continued movements of the contacts aftertheir elasticdeformation has reached its maximum, will depend on theseforcm, and the mutual relations of these forces probablydeterminewhether the contacts will reach the state of rest with orWithout repeated interruptions and closures. vThere are indications thatthe contacts will reach thestate of rest without interruptions on thecondition that the pressure existing between the conacts when theirelastic deformation has reached its maximum,- does not exceed the sum ofthe force caused by the abovementioned deflection of the movable contactspring and the contact pressure existing between the contacts when theyhave come to rest, but it has not been established to a certainty thatthe fulfilment of this condition is necessary or suificient in orderthat contact vibrations shall be avoided. The movements of the contactswith respect to each other will of course also be dependent in a highdegree on the natural frequencies of vibration of the contact springsand the phase angles of the vibrations occurring during the closureperiod. It has proved that the liability to contact bouncing is reducedif the natural frequency of vibration of the fixed contact spring isequal to orsomewhat higher than that'ofthe movable spring. i

The contact pressure existing between the contacts when they have cometo rest in engagement with each other, is determined by thedimensionsand the material of the contacts and the contact springs, theinitial tension of the springs and the distance between their fixedends. These factors also determine the movements of the contacts duringthe closing process, and it is obvious that if a contactdeviceisdesigned with a view to have a certain ratio of the contact pressure to.the weight of the free ends of the contact springs, the movements of thecontact duringthe closing process will also be deof a fixed contactspring and arranged for indirect operation; said fixed contact springbeing more rigid than'either of its associated movable contact springs;both of said movable contact springs being pre-tensioned toward theirassociated fixed contact spring so as to yield at the contact points aforce amounting to at least 50 times the weight of the movable part ofthe contact spring inclusive contacts and wherein the natural frequencyof vibration of the fixed contact springs inclusive their contacts issomewhat higher than the natural frequency of vibration of the mov-'able contact springs inclusive their contacts; and contact actuatingmeans positioned between the movable contact springs and movable in onedirection to a first fixed po'sition to move the make-contact springawayfrom said fixed contact spring and allow the Contact on thebreakcontact spring to close against the contact on the fixed contactspring solely due to said pre-tension force and movable in the otherdirection to a second fixed position to move the break-contact springaway from said fixed contact spring and allow the contact on themake-contact spring to close against the contact on the fixed contactspring solely due to said pre-tension force.

15. A switching device comprising in combination an energizing coil; amagnet core; an armature; fixed contact springs; a pair of movablecontact springs mounted on opposite sides of a fixed contact spring andadapted to alternately engage the fixed contact spring; said fixedcontact springs being more rigid than the movable contact springs; saidmovable contact springs each being pre-tensic-ned so thattheir free endsare biased toward their associated fixed contact springs to yield at thecontact points a force amounting to at least 50 times the weight of themovable part of the contact spring inclusive the contacts; apre-tensioning spring; and contact actuating means positioned betweenthe pair of movable contact springs and movable to a first fixedposition to move one of said pairs of movable contact springs away fromits associated fixed contact spring and allow the contact on the otherpsaid pair of movable contact springs to close against the contact on thefixed contact spring solely due to said pie-tension force of said othermovable contact spring, and movable to a second fixed position to movesaid other movable contact spring away from said fixed contact springand allow the contact on said one movable contact spring to closeagainst the contact on said fixed contact spring solely due to saidpre-tension force of said one movable contact spring; said actuatingmeans being operatively associated with said armature and saidpretensioning spring and the pre-tensioning spring being tensioned toexert a force upon the contact actuating means which force is oppositelydirected to the force exerted upon the contact actuating means by thearmature when attracted.

References Cited by the Examiner The following references, cited by theExaminer, are of record in the patented file of this patent or theoriginal patent.

UNITED STATES PATENTS Johnson 20 6 6 1,697,872 1/29 2,178,656 11/39Swenson 200-87 2,282,687 5/42 Vigren et a1 200-1 2,290,725 7/42 Bartelset a1. 200-166 2,339,610 1/44 Baker 200-104 2,368,201 1/45 Clare 200-1042,393,901 1/46 iaigh et a1 200-104 2,562,091 7/51 Harrison 200-1042,577,468 12/51 Knos -2 200-104 2,587,458 2/52 Tritts 200-166 2,590,9964/52 Miloche 200-104 2,612,367 9/ 52 Blomquist 200-1 2,616,993 11/52Koohler 200-1 FOREIGN PATENTS 730,125 5/55 Great Britain. 125,889. 8/ 49Sweden.

BERNARD A. GILHEANY, Primary Examiner.

Feb. 23, 1 965 P. E. SEABORN 25,732

APPARATUS FOR SORTING ARTICLES Original Filed March 15, 1959 6Sheets-Sheet 1 Ji 1 I I Em C I o E P m (I) 3 F INVENTOR PAUL E. SEABORNATTORNEY

